plat/arm/board/arm_fpga: Enable port for alternative cluster configurations

plat/arm/board/arm_fpga: Enable port for alternative cluster configurations

This change is part of the goal of enabling the port to be compatible
with multiple FPGA images.

The BL31 port that is uploaded as a payload to the FPGA with an image
should cater for a wide variety of system configurations. This patch
makes the necessary changes to enable it to function with images whose
cluster configurations may be larger (either by utilizing more
clusters, more CPUs per cluster, more threads in each CPU, or a
combination) than the initial image being used for testing.

As part of this, the hard-coded values that configure the size of the
array describing the topology of the power domain tree are increased
to max. 8 clusters, max. 8 cores per cluster & max 4 threads per core.
This ensures the port works with cluster configurations up to these
sizes. When there are too many entries for the number of available PEs,
e.g. if there is a variable number of CPUs between clusters, then there
will be empty entries in the array. This is permitted and the PSCI
library will still function as expected. While this increases its size,
this shouldn't be an issue in the context of the size of BL31, and is
worth the trade-off for the extra compatibility.

Signed-off-by: Oliver Swede <oli.swede@arm.com>
Change-Id: I7d4ae1e20b2e99fdbac428d122a2cf9445394363